It's unfortunate since ideally any contribution is a good contribution, but the Linux kernel has been so highly dependent on maintainers, that them being highly protective of their time is totally warranted.

As someone who works at a big corp with regular OSS contributions, this doesn't surprise me at all. Recently a "Look at how amazing we are" e-mail was sent out to my team touting the number of PRs submitted to a widely-used OSS project.

If your management incentivizes it, you'll try to game the system.